<?php
/**
 * PHPExcel
 *
 * Copyright (c) 2006 - 2013 PHPExcel
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 *
 * @category   PHPExcel
 * @package    PHPExcel_CachedObjectStorage
 * @copyright  Copyright (c) 2006 - 2013 PHPExcel (http://www.codeplex.com/PHPExcel)
 * @license    http://www.gnu.org/licenses/old-licenses/lgpl-2.1.txt	LGPL
 * @version    1.7.9, 2013-06-02
 */


/**
 * PHPExcel_CachedObjectStorage_DiscISAM
 *
 * @category   PHPExcel
 * @package    PHPExcel_CachedObjectStorage
 * @copyright  Copyright (c) 2006 - 2013 PHPExcel (http://www.codeplex.com/PHPExcel)
 */
class PHPExcel_CachedObjectStorage_DiscISAM extends PHPExcel_CachedObjectStorage_CacheBase implements PHPExcel_CachedObjectStorage_ICache {

	/**
	 * Name of the file for this cache
	 *
	 * @var string
	 */
	private $_fileName = null;

	/**
	 * File handle for this cache file
	 *
	 * @var resource
	 */
	private $_fileHandle = null;

	/**
	 * Directory/Folder where the cache file is located
	 *
	 * @var string
	 */
	private $_cacheDirectory = null;


	/**
	 * Store cell data in cache for the current cell object if it's "dirty",
	 *     and the 'nullify' the current cell object
	 *
	 * @return    void
	 * @throws    PHPExcel_Exception
	 */
	protected function _storeData() {
		if ($this->_currentCellIsDirty)
		{
			$this->_currentObject->detach();

			fseek($this->_fileHandle, 0, SEEK_END);
			$offset = ftell($this->_fileHandle);
			fwrite($this->_fileHandle, serialize($this->_currentObject));
			$this->_cellCache[$this->_currentObjectID] = array(
					'ptr' => $offset,
					'sz' => ftell($this->_fileHandle) - $offset
			);
			$this->_currentCellIsDirty = false;
		}
		$this->_currentObjectID = $this->_currentObject = null;
	} //	function _storeData()


	/**
	 * Add or Update a cell in cache identified by coordinate address
	 *
	 * @param    string        $pCoord Coordinate address of the cell to update
	 * @param    PHPExcel_Cell $cell   Cell to update
	 *
	 * @return    void
	 * @throws    PHPExcel_Exception
	 */
	public function addCacheData($pCoord, PHPExcel_Cell $cell) {
		if (($pCoord !== $this->_currentObjectID) && ($this->_currentObjectID !== null))
		{
			$this->_storeData();
		}

		$this->_currentObjectID = $pCoord;
		$this->_currentObject = $cell;
		$this->_currentCellIsDirty = true;

		return $cell;
	} //	function addCacheData()


	/**
	 * Get cell at a specific coordinate
	 *
	 * @param    string $pCoord Coordinate of the cell
	 *
	 * @throws    PHPExcel_Exception
	 * @return    PHPExcel_Cell    Cell that was found, or null if not found
	 */
	public function getCacheData($pCoord) {
		if ($pCoord === $this->_currentObjectID)
		{
			return $this->_currentObject;
		}
		$this->_storeData();

		//	Check if the entry that has been requested actually exists
		if (!isset($this->_cellCache[$pCoord]))
		{
			//	Return null if requested entry doesn't exist in cache
			return null;
		}

		//	Set current entry to the requested entry
		$this->_currentObjectID = $pCoord;
		fseek($this->_fileHandle, $this->_cellCache[$pCoord]['ptr']);
		$this->_currentObject = unserialize(fread($this->_fileHandle, $this->_cellCache[$pCoord]['sz']));
		//    Re-attach this as the cell's parent
		$this->_currentObject->attach($this);

		//	Return requested entry
		return $this->_currentObject;
	} //	function getCacheData()


	/**
	 * Get a list of all cell addresses currently held in cache
	 *
	 * @return  array of string
	 */
	public function getCellList() {
		if ($this->_currentObjectID !== null)
		{
			$this->_storeData();
		}

		return parent::getCellList();
	}


	/**
	 * Clone the cell collection
	 *
	 * @param    PHPExcel_Worksheet $parent The new worksheet
	 *
	 * @return    void
	 */
	public function copyCellCollection(PHPExcel_Worksheet $parent) {
		parent::copyCellCollection($parent);
		//	Get a new id for the new file name
		$baseUnique = $this->_getUniqueID();
		$newFileName = $this->_cacheDirectory . '/PHPExcel.' . $baseUnique . '.cache';
		//	Copy the existing cell cache file
		copy($this->_fileName, $newFileName);
		$this->_fileName = $newFileName;
		//	Open the copied cell cache file
		$this->_fileHandle = fopen($this->_fileName, 'a+');
	} //	function copyCellCollection()


	/**
	 * Clear the cell collection and disconnect from our parent
	 *
	 * @return    void
	 */
	public function unsetWorksheetCells() {
		if (!is_null($this->_currentObject))
		{
			$this->_currentObject->detach();
			$this->_currentObject = $this->_currentObjectID = null;
		}
		$this->_cellCache = array();

		//	detach ourself from the worksheet, so that it can then delete this object successfully
		$this->_parent = null;

		//	Close down the temporary cache file
		$this->__destruct();
	} //	function unsetWorksheetCells()


	/**
	 * Initialise this new cell collection
	 *
	 * @param    PHPExcel_Worksheet $parent The worksheet for this cell collection
	 * @param                       array   of mixed        $arguments    Additional initialisation arguments
	 */
	public function __construct(PHPExcel_Worksheet $parent, $arguments) {
		$this->_cacheDirectory = ((isset($arguments['dir'])) && ($arguments['dir'] !== null)) ? $arguments['dir'] : PHPExcel_Shared_File::sys_get_temp_dir();

		parent::__construct($parent);
		if (is_null($this->_fileHandle))
		{
			$baseUnique = $this->_getUniqueID();
			$this->_fileName = $this->_cacheDirectory . '/PHPExcel.' . $baseUnique . '.cache';
			$this->_fileHandle = fopen($this->_fileName, 'a+');
		}
	} //	function __construct()


	/**
	 * Destroy this cell collection
	 */
	public function __destruct() {
		if (!is_null($this->_fileHandle))
		{
			fclose($this->_fileHandle);
			unlink($this->_fileName);
		}
		$this->_fileHandle = null;
	} //	function __destruct()

}
